Ridge had been supporting former Florida Gov. Jeb Bush, who dropped out of the race after a poor showings in Iowa, New Hampshire and South Carolina. In 2008, Ridge backed U.S. Sen. John McCain for president.

Ridge, a former Congressman, issued the following statement: "I want to see proven conservative leadership in our nominee, not just the promise of conservative leadership, and that's why John Kasich is my candidate. I've known him for more than 30 years, since we came to Congress together, and I've always respected the way he successfully unites people of different views to enact conservative policies. He did it in Ohio and helped turn around his state and he did it as chief architect of the balanced budget in Washington -- something we haven't seen since he left. John Kasich also has both the strong command of national security and foreign policy issues that a president needs as well as the executive experience it takes to actually be Commander-in-Chief. He is ready to be president on Day One."

Also on Monday, former Minnesota Gov. Tim Pawlenty endorsed U.S. Sen. Marco Rubio of Florida for the GOP nomination.